Evaluation of gastric intramucosal pH measurements with tissue oxygenation indices in patients with severe sepsis

Abstract

In this study tonometric measurements of gastric intramucosal pH (pHi) were compared with oxygen delivery (DO2), oxygen consumption (VO2) and arterial lactate as systemic indices of tissue oxygenation in patients with severe sepsis. Dobutamine was infused at increasing doses of 5-10 μg/kg/min at 60-minute intervals in 24 patients. DO2 was calculated as the product of cardiac index (CI) and arterial oxygen content. VO2 was determined directly from expired gas analysis (mVO2) and, indirectly, by calculating the product of cardiac index (CI) and arteriovenous oxygen content difference (cVO2). pHi was obtained by gastric tonometry. After each dose administration of dobutamine mVO2, cVO2, DO2, lactate levels and pHi were determined. The phenomenon of oxygen supply dependency (OSD), as characterised by a linear relationship, was found when the pooled data of both measured and calculated oxygen consumption were plotted against the corresponding level of oxygen delivery (DO2 to cVO2: y=0.34x-106.4, r=0.05 (p<0...